Mr. R, Spruce on the Musci and Hepatice of the Pyrenees. 97 
cupies has in both countries the same average annual temperature. 
Were this the case, such discrepancies as the following would be 
inexplicable. On Mount Etna, the beech, the birch and the 
Scotch fir are said to occupy the same zone. In the Pyrenees 
the beech ceases before the Scotch fir begins, and in the Alps 
the birch is said to fail even below the spruce-fir. But in Lap- 
land the birch extends far above the Scotch fir, and in fact 
ascends higher on the mountains than any other tree. Assuming 
the correctness of these observations (which for Lapland and the 
Alps cannot be questioned), we are bound to conclude that there 
are peculiarities of constitution in certain species which enable 
them to ascend proportionally higher in one latitude than in 
another *. In other words, an alpine flora is not necessarily an 
arctic flora, in its character. Hence the saying of Linneus, 
“ Plante diverse indicant altitudinem perpendicularem terre,” 
must be regarded not as an axiom but asa problem, the complete 
solution of which still remains to be effected. 
It will readily be admitted that all our artificial arrangements, 
'* The discussion of this tdiosyncrasy would demand an entire volume, 
but Wahlenberg’s explanation of it (Flora Lapponica, Intred.) is worth 
quoting, and should be borne in mind in comparing the flora of the Pyrenees 
or of the Alps with that of Lapland. ‘‘ Valde probabile mihi videtur a calore 
meridiano vegetationisgradum preecipue pendere”’(p. xlix, l. c.)—“Temperies 
tantum illa esdivalis in vegetatione producenda efficax, constituit clima, 
ejusque gradus determinat.” (p. lii.)—‘* Alize plantze longam magis, quam ca- 
lidam estatem sibi exposcunt: ubi temperatura zstivalis media per tres men- 
ses gradum 8°-5 (Centigr.) haud attingit, ibi hordeum haud ad maturitatem 
pervenire potest. Hoc quidem jamdudum infra Enontekis contingit ; sed 
nihilominus tamen arbores varie estate brevi et calida hujus regionis con- 
tente sunt: Betule enim et Salices alpes versus longe altius late propa- 
gantur. Arbores conifer fere ac Hordeum estatem longiorem quamquam 
temperatiorem, requirunt, itaque longe altius ascendunt in alpibus Helve- 
ticis quam Betula, &c. Ex observationibus thermometricis allatis constat, 
@statem in alpibus Helveticis, etiamsi temperatior sit, fere longiorem esse, 
quam in alpibus Lapponicis; et pro certo scimus, temperaturam mediam 
omnium mensium per totum annum eo magis zquabilem esse in montibus 
Andium Americz meridionalis, et igitur omnes arbores, calidiorem quam 
longiorem zstatem requirentes, ibi crescere desinunt duplo longius infra 
limitem nivalem quam apud nos; sed Hordeum aliaque Cerealia temperie 
moderata 7 vel 8 graduum contenta, si ea modo longior sit, duplo altius 
versus limitem nivalem ibi adseendunt quam omnes arbores.” (p. liii.) 
It is also well known that some plants will bear forcing, that is, will sur- 
vive and flourish under constant excitement and irritation, much better than 
others ; hence we could hardly expect any plant which will not bear some 
degree of forcing, to thrive in the rapid summer, with its long days and 
proportionally great meridional heat, of countries bordering on the Arctic 
circle ; should it even subsist through the rigorous winter of that region. 
I am sensible how much the absence of exact thermometrical observa- 
tions takes away from the completeness of this sketch of part of the flora 
of the Pyrenees. I have none of my own to adduce, except a few made at 
the foot of the Western Pyrenees in the month of June, when I found the 
meridional temperature to often exceed 90° Fahrenheit. 
Ann. & Mag. N. Hist. Ser. 2. Vol. in. 7 
